Vehicle fuel systems include evaporative emission control systems designed to reduce the release of fuel vapors to the atmosphere. For example, vaporized hydrocarbons (HCs) from a fuel tank may be stored in a fuel vapor canister packed with an adsorbent which adsorbs and stores the vapors. At a later time, when the engine is in operation, the evaporative emission control system allows the vapors to be purged into the engine intake manifold for use as fuel.
Purging vapors from the fuel vapor canister may involve opening a canister purge valve coupled to a conduit between the fuel vapor canister and the intake manifold. Over the course of vehicle operation, the canister purge valve may entrap contaminants or other debris originating from components of the fuel system. These contaminants may be trapped on a seal in the canister purge valve and may prevent the canister purge valve from closing completely. These contaminants may be more likely to become entrapped in hybrid vehicles where the internal combustion engine, and accordingly, the purge valve may be inoperative for longer periods of time. A diagnostic routine performed to test the emission control system may detect the presence of a leak in the system if the seal in the canister purge valve cannot close completely due to the presence of contaminants. The inventors herein have recognized that reducing the trapping of contaminants on the seal may reduce a likelihood of such contaminant-sourced leaks.
Thus, in one example, a method for operating a purge valve coupled to a fuel vapor canister, having a valve body including an armature engaging and disengaging with the valve body, is provided. The method comprises opening and closing the valve body via the armature to selectively enable purge flow during a purge operation of the fuel vapor canister, and ratcheting the armature with each actuation of the valve body to rotate the armature about a central longitudinal axis. By rotating the armature, contaminants trapped on a seal attached to an end of the armature may be dislodged so that the valve can fully seal.
In another example, a method is provided for a canister purge valve comprising rotating an armature within a valve body as the canister purge valve opens and closes during a canister purge operation, the armature encircled at a first end by an elastomer seal with multiple angled wings. The multiple angled wings on the elastomer seal may enable a gradual rotation of the armature which may help clear trapped contaminants.
For example, a canister purge valve in a fuel system of a vehicle may comprise a valve body including a stator assembly and an armature-seal assembly. Herein the canister purge valve may be a solenoid valve and the vehicle may be a hybrid electric vehicle (HEV). The stator assembly may include a stator surrounded by a coil coupled to a power source. The armature-seal assembly may comprise an armature wherein a first end of the armature is surrounded substantially by an elastomer seal, and the elastomer seal may obstruct an aperture within the valve body. Further, the elastomer seal may be configured with a plurality of wings around its circumference. The aperture within the valve body may enable communication of the valve body, and thereby, a fuel vapor canister, with an intake manifold of an engine. The aperture may be normally closed by the elastomer seal when the stator assembly is de-energized. When canister purge operation is enabled, a pulse width modulated signal may be communicated to the solenoid valve. The stator assembly may be energized and as a result, the armature along with the elastomer seal may be pulled away from the aperture on the valve body allowing fluidic communication between the intake manifold and the fuel vapor canister. As the valve is pulsed and the stator assembly is energized and de-energized, wings on the circumference of the elastomer seal may vary between a stressed, flattened position and an un-stressed, inclined position, providing a gradual rotation of the armature body. As the armature-seal assembly rotates, contaminants trapped on an underside of the elastomer seal may be displaced and released into the intake via the aperture.
In this way, leaks in the canister purge valve due to contaminants may be reduced. Contaminants trapped on a surface of the seal of the armature-seal assembly in the canister purge valve may be flushed out by enabling a rotation of the armature body. Thus, a potential leak source may be mitigated and the seal may occlude the aperture fully as the stator assembly is de-energized. By reducing the likelihood of leaks resulting from the trapping of contaminants, operation of the canister purge valve may be enhanced. Further, a probability of detecting leaks in the canister purge valve during diagnostic routines may be diminished. As such, diagnostic routines may be completed without a malfunction indicator light being actuated, which may in turn prevent unnecessary and costly diagnostics and maintenance from being carried out.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.